Effectiveness of two sequences of Toxoplasma gondii SAG2 protein to differentiate toxoplasmosis infection stages by measuring IgG, IgA and IgM antibodies

Abstract

Here, we evaluated two Toxoplasma gondii SAG2 antigen sequences which differ in thepresence of the amino-and carboxy-terminal sequences in one of them. They were testedwith several techniques to differentiate between acute and chronic phase of toxoplasmosis:avidity assay and indirect ELISA for the detection of anti-Toxoplasma IgG, IgA and IgMantibodies. Significant differences were found between them. The best results were obtainedwith the sequence denominated SAG2c, which yielded sensitivity of 73.8% and specificity of 80.3% in the detection of IgG by ELISA. Measurement of IgA yielded 67.2% and 81.8% of sensitivity and specificity, respectively. The avidity assay yielded 100% sensitivity and 81.82% specificity. Finally, the molecular modeling and epitope predictions of the protein are developed to find the antigenic region locations, specific and nonspecific, on three-dimensional structure. This paper is the first report of promising results of SAG2 used for detecting IgA antibodies to differentiate toxoplasmosis infection stages.